1. Field of the Present Invention
The invention is in the field of data processing systems and more particularly power management within a data processing system.
2. History of Related Art
As the packing density and computing frequency of data processing system (computer) components increases, their power consumption becomes a limiting factor for computing advancements. Cooling system designs and power supply designs are stretched to the limit to support the growing thermal and power budgets of computing systems. The wide variability in system activity with workload and consequent variability in power consumption imply that while significantly smaller cooling and power resources would suffice for many workloads, systems need to tolerate occasional bursts of activities that require significantly higher capacities for system stability.
Current approaches to system design include careful estimation of maximum individual component power consumption for component-wise budgets and power supply design. These approaches tend to design power supplies to accommodate the sum of all individual power budgets with some educated/experience-based adjustments. In practice, however, component-wise maximum budgets are rarely if ever realized in a system at the same time. This implies that systems are designed with a higher supply and cooling capacity than is required in practice. When system designs get too aggressive to avoid this waste or attempt to reduce cooling and power supply design costs, an opposing problem (i.e., insufficient power supply) may result, especially for short periods of intense workload activity. To prevent permanent system damage, power supplies are designed to shutdown when oversubscribed, which is obviously an undesirable resolution of the problem.
Conventional approaches to limiting power consumption to avoid oversubscribed systems tend to share some or all of the following limitations. Conventional techniques focus on regulating the power consumption and temperature of individual components through component-specific activity regulating techniques. While this approach may be sufficient for addressing problems associated with a single component or addressing problems associated with a system whose power consumption is dominated by a single component, it is not sufficient for larger systems having multiple significant power consumers. Even in a tightly coupled system where activity of a single component can determine overall system activity, the ability to manage multiple components gives greater flexibility and can be more effectively exploited to reduce the performance impact of regulating activity.
Conventional power conservation techniques tend to focus on the management of power states and operating modes of individual/multiple components. While exploiting the power states of computing components is important for power management, it is not usually sufficient for effective power management as it does not address the variability of power consumption with activity for computing components, i.e., there can be significant variation in power consumption of a computing component event within a specific power state based on the level of activity.
Conventional power conservation techniques also tend to require significant enhancement to existing systems to support adherence to a power budget in the face of increased activity.
It would be desirable to provide a power conservation methodology using an approach to ensuring stable operation of the system within significantly lower power budgets and consequently smaller cooling resources while reducing the occasional negative impact of the reduced power budgets on system performance.